This application generally relates to digital image processing, and more particular, to a first-in-first-out (FIFO) buffered median scene non-uniformity correction method.
Digital sensors exhibit certain noise characteristics that result in some degree of image degradation in the final output. One image degradation problem of concern is residual Fixed Pattern Noise (FPN) which may be present after typical Non-Uniformity Correction algorithms have been performed. Distinguishing and effectively removing this noise traditionally has been difficult without degrading the high frequency spatial content of the image.
Conventional non-uniformity correction (NUC) methods have attempted to identify high frequency scene content areas and avoid further processing in those areas in a given frame. These methods converge slowly to minimize the effect of temporal noise and scene content impacting FPN correcting terms. Rapid changes in input scene intensity thus result in correspondingly rapid changes in FPN, which are not fully corrected. An additional problem with these approaches is that outlying pixels may be difficult to distinguish from high frequency content and, as a result, residual FPN artifacts can be present in an image. These artifacts may look like random “spots”, “lines” and/or other visible artifacts to the end-user.
Thus, an improved scene non-uniformity correction method is desired which preserves the true image spatial context while removing noise.